Large CNC machine for crankshaft company

Mick Harwood, managing director, says: “We have grown our sub-contract shaft and crankshaft business over the years with 2009 being our best trading year thus far, and as part of our ongoing strategy, additional investment in new plant and equipment was required in order to achieve the next stage of our company development. We looked closely at the global market for a suitable machine and whilst there are a number of manufacturers offering machines of the size required, we didn’t just want another large capacity CNC grinding machine. Almost by accident we discovered that Broadbent Stanley, the famous Yorkshire based large lathe and grinding machine manufacturer were in final stages of development of a large capacity orbital grinding machine – just what we needed.”

Orbital grinding is not a new process but machines the size of the new Broadbent Stanley Orbigrind with a maximum distance between centres of 11,000mm and swing of 1900mm, under full CNC control, had proven nigh on impossible to produce in the past. Conventional CNC machines use recirculating ballscrew drives via AC motors, and whilst lost motion or backlash is minimal when new, after a short period of time, constantly reversing a crosslide/wheelhead assembly weighing some 7 or 8 tonnes would soon introduce inaccuracies, with excessive wear in the ballscrew/drive taking place. So, a completely new drive system was developed using linear motor technology and whilst more expensive, it is claimed to completely eliminate the need for conventional drives, and give micron accuracy.

Although still is the early stages of machine usage, LC&M has already achieved major savings in both set-up and machining times. The company says that gone are the days of individually clocking each bearing or ‘pin’ diameter, prior to grinding, as all is accommodated within the control software. “Once fully proficient” Harwood adds, “we believe we can slash up to 60% off setting times alone, this will give us better throughput, a reduction in lead time, which in turn will make us more competitive in the market place.”

LC&M was founded eight years ago from the Clark Crank & Forge Company and specialises in manufacturing one-off and small batch production of shafts and crankshafts up to 11metres in length. In the first year of trading, a turnover of £150,000 was achieved rising to almost £9 million in 2009.

In addition to the manufacture of new crankshafts, LC&M also has forging and repair divisions, and offers a sub-contract facility for the general machining/grinding of large shafts.